CN112204847A

CN112204847A - Power transmission device and control method for power transmission device

Info

Publication number: CN112204847A
Application number: CN201880093996.1A
Authority: CN
Inventors: 寺田行太
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2018-05-28
Filing date: 2018-05-28
Publication date: 2021-01-08
Anticipated expiration: 2038-05-28
Also published as: EP3806285A4; US20210197677A1; WO2019229808A1; JPWO2019229808A1; EP3806285B1; CN112204847B; JP6958733B2; EP3806285A1

Abstract

A power transmission device (300) is provided with: a power transmission coil (42) for supplying power to a power receiving coil (22) provided on a vehicle (10) in a non-contact manner, a cover (43) for covering at least an upper surface of the power transmission coil (42) in the axial direction, a foreign object detection coil (41) disposed between the power transmission coil (42) and the cover (43), and a lifting mechanism (17) for maintaining a space between the power transmission coil (42) and the foreign object detection coil (41) and lifting and lowering the power transmission coil (42) and the foreign object detection coil (41) relative to the ground. The foreign object detection coil (41) is disposed at a predetermined distance from the cover (43) in the axial direction before detecting foreign objects. When the foreign matter detection coil (41) detects foreign matter, the lifting mechanism (17) lifts the foreign matter detection coil (41) so that the distance between the foreign matter detection coil (41) and the cover (43) is shorter than a predetermined distance.

Description

Power transmission device and control method for power transmission device

Technical Field

The present invention relates to a power transmission device and a control method for the power transmission device.

Background

Conventionally, a technique for supplying power from a power transmission coil provided on a ground surface to a power reception coil provided on a vehicle in a non-contact manner is known (patent document 1). The invention described in patent document 1 provides an air layer between the power transmission coil and the cover covering the power transmission coil, thereby reducing transmission of joule heat from the power transmission coil to the cover.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-103645

A foreign object detection coil may be provided axially above the power transmission coil. If the invention described in patent document 1 is applied and an air layer is provided between the foreign object detection coil and the cover, the distance between the foreign object detection coil and the cover becomes long. This may reduce the foreign object detection accuracy.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object thereof is to provide a power transmitting device and a method for controlling the power transmitting device, which can improve the accuracy of detecting foreign matter while restricting heat transfer between a power transmitting coil and a cover.

A power transmission device according to an aspect of the present invention includes: a power transmission coil that contactlessly transmits power to a power reception coil provided on a vehicle; a cover that covers at least an axially upper face of the power transmitting coil; a foreign object detection coil disposed between the power transmission coil and the cover; and a lifting mechanism for maintaining the interval between the power transmission coil and the foreign body detection coil and lifting and lowering the power transmission coil and the foreign body detection coil relative to the ground. When the foreign object detection coil detects a foreign object, the lift mechanism lifts the foreign object detection coil so that the distance between the foreign object detection coil and the cover is shorter than a predetermined distance.

According to the present invention, the foreign object detection accuracy can be improved while limiting the heat transfer between the power transmission coil and the cover.

Drawings

Fig. 1 is a schematic configuration diagram of a contactless power supply system according to an embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of the contactless power supply according to the embodiment of the present invention.

Fig. 3A is a diagram illustrating a standby state of the embodiment of the present invention.

Fig. 3B is a diagram illustrating a foreign object detection state according to the embodiment of the present invention.

Fig. 3C is a diagram illustrating a state of charge according to the embodiment of the present invention.

Fig. 4 is a graph showing a relationship between a distance between the power transmitting coil and the cover and a temperature of the power transmitting coil. Fig. 4 is a graph showing a relationship between a distance between the power transmission coil and the cover and an induced voltage of the power reception coil.

Fig. 5 is a graph showing the relationship between time and component protection temperature.

Fig. 6 is a flowchart illustrating an operation example of the contactless power supply system according to the embodiment of the present invention.

Fig. 7 is a flowchart illustrating an operation example of the contactless power supply system according to the embodiment of the present invention.

Fig. 8A is a diagram illustrating a standby state in modification 1 of the present invention.

Fig. 8B is a diagram illustrating a foreign object detection state in modification 1 of the present invention.

Fig. 8C is a diagram illustrating a charged state in modification 1 of the present invention.

Fig. 9A is a diagram illustrating a standby state in modification 2 of the present invention.

Fig. 9B is a diagram illustrating a foreign object detection state in modification 2 of the present invention.

Fig. 9C is a diagram illustrating a charged state in modification 2 of the present invention.

Fig. 10A is a diagram illustrating a charged state in modification 3 of the present invention.

Fig. 10B is a diagram illustrating a foreign object detection state according to modification 3 of the present invention.

Fig. 10C is a diagram illustrating a charged state in modification 3 of the present invention.

Fig. 11A is a diagram illustrating a standby state in modification 4 of the present invention.

Fig. 11B is a diagram illustrating a foreign object detection state and a charging state according to modification 4 of the present invention.

Fig. 12 is a flowchart illustrating an operation example of the non-contact power supply system according to modification 4 of the present invention.

Fig. 13 is a flowchart illustrating an operation example of the non-contact power supply system according to modification 4 of the present invention.

Fig. 14A is a diagram illustrating a standby state in modification 5 of the present invention.

Fig. 14B is a diagram illustrating a foreign object detection state and a charging state in modification 5 of the present invention.

Fig. 15 is a flowchart illustrating an operation example of the contactless power supply system according to the embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same reference numerals are given to the same parts, and the description thereof is omitted.

(Structure of non-contact Power supply System)

The configuration of the contactless power supply system will be described with reference to fig. 1 and 2. As shown in fig. 1, the contactless power supply system includes: a power feeding device 100 as a ground-side unit, and a power receiving device 200 as a vehicle-side unit. The non-contact power feeding system feeds power from a power feeding device 100 disposed at a power feeding station or the like to a power receiving device 200 mounted on a vehicle 10 such as an electric vehicle or a hybrid vehicle in a non-contact manner, and charges a battery 27 mounted on the vehicle 10.

Power feeding device 100 includes power transmitting device 300 disposed in a parking space near a power feeding station. The power transmission device 300 includes: power transmission coil 42, ground fixing unit 15, lifting mechanism 17, drive control unit 18, and distance sensor 20. Power receiving device 200 includes power receiving coil 22 provided on the bottom surface of vehicle 10. The power receiving coil 22 is arranged to be opposed to the power transmitting coil 42 when the vehicle 10 is parked to a prescribed position (power suppliable position) of a parking space. In addition, the power receiving coil 22 may be provided so as to be swingable via an underfloor swing structure of the vehicle 10. The power transmitting apparatus 300 and the power receiving apparatus 200 may include a resonant capacitor.

The power transmission coil 42 is formed of a primary coil formed of litz wire, and transmits power to the power reception coil 22. The power receiving coil 22 is also composed of a secondary coil composed of litz wire, and receives electric power from the power transmitting coil 42. Due to the electromagnetic induction between the two coils, power can be supplied from the power transmission coil 42 to the power reception coil 22 in a non-contact manner. The non-contact power feeding method is not limited to the electromagnetic induction type, and may be a magnetic field resonance type or the like.

The ground fixing portion 15 is a device fixed to the ground. Power transmission coil 42 ascends and descends with respect to ground fixing unit 15. In other words, power transmitting coil 42 is raised and lowered with respect to the ground.

The drive control unit 18 receives a signal from the control unit 14, and controls the actuator 44 based on the received signal (see fig. 3A to 3C). The drive control unit 18 and the actuator 44 will be described in detail later.

The lifting mechanism 17 raises, lowers, or stops the power transmission coil 42 in the vertical direction by the power of the actuator 44.

The distance sensor 20 measures the distance between the power transmitting coil 42 and the power receiving coil 22. In addition, the distance sensor 20 transmits the measured distance to the control unit 14. The control unit 14 controls the drive control unit 18 based on the distance acquired from the distance sensor 20. The power receiving coil 22 may also be moved in the vertical direction, similarly to the power transmitting coil 42.

The power supply device 100 includes: a power control unit 11, a wireless communication unit 13, and a control unit 14.

The power control unit 11 is a circuit for converting ac power transmitted from the ac power supply 110 into ac power of high frequency and transmitting the ac power to the power transmission coil 42. The power control unit 11 includes: a rectifying section 111, a PFC circuit 112, a DC power supply 114, and an inverter 113.

The rectifier 111 is electrically connected to the ac power supply 110, and is a circuit for rectifying ac power output from the ac power supply 110. The PFC circuit 112 is a Power Factor Correction (PFC Correction) circuit for improving a Power Factor by shaping a waveform output from the rectifier 111, and is connected between the rectifier 111 and the inverter 113.

The inverter 113 has a PWM control circuit including switching elements such as IGBTs, and converts direct current into alternating current based on switching control signals to supply power to the power transmission coil 42. The DC power supply 114 outputs a DC voltage when the power transmission coil 42 is weakly excited.

The wireless communication section 13 performs wireless local area network (wifi) communication with a wireless communication section 23 provided on the vehicle 10.

The control unit 14 is a controller that controls the entire power supply device 100, and includes: an inverter control unit 141, a PFC control unit 142, and a sequence control unit 143. When the vehicle 10 is parked in the parking space, the control unit 14 executes a process of determining the parking position. At this time, the PFC control unit 142 generates an excitation electric command, and the inverter control unit 141 generates a frequency command, a duty ratio, and the like of the excitation electric to control the inverter 113. Thereby, the control unit 14 transmits the electric power for determining the parking position from the power transmission coil 42 to the power reception coil 22. When the parking position determination process is performed, the control unit 14 weakly excites or weakly excites the power transmission coil 42 to transmit electric power for parking position determination. The sequence control unit 143 exchanges sequence information with the power receiving apparatus 200 via the wireless communication unit 13. The weak excitation or weak excitation is an excitation weaker than that in normal charging and weak excitation to the extent that it does not affect the surroundings. The control unit 14 and the drive control unit 18 are, for example, general-purpose microcomputers each including a CPU (central processing unit), a memory, and an input/output unit.

The power receiving device 200 includes: power receiving coil 22, wireless communication unit 23, charging control unit 24, rectifying unit 25, relay switch 26, battery 27, inverter 28, motor 29, and notification unit 30.

The wireless communication unit 23 performs bidirectional communication with the wireless communication unit 13 provided in the power supply apparatus 100.

The charge control unit 24 is a controller for controlling the charging of the battery 27. When the vehicle 10 is parked in the parking space, the charging control unit 24 executes a process of determining the parking position. At this time, the charging control unit 24 monitors the power received by the power receiving coil 22. Then, the charging control unit 24 detects the position of the power receiving coil 22 based on the voltage received by the power receiving coil 22 when the power transmitting coil 42 is excited. Further, charging control unit 24 controls wireless communication unit 23, notification unit 30, relay switch 26, and the like, and transmits a signal indicating the start of charging to control unit 14 of power feeding apparatus 100 via wireless communication unit 23.

The rectifier 25 is connected to the power receiving coil 22, rectifies the ac power received by the power receiving coil 22 into dc power, and outputs the dc power to the battery 27 and the inverter 28 (see fig. 2).

Relay switch 26 is switched on and off by the control of charging control unit 24. When the relay switch 26 is off, the battery 27 and the rectifier 25 are electrically isolated from each other (see fig. 2). The battery 27 is configured by connecting a plurality of secondary batteries and serves as a power source of the vehicle 10.

The inverter 28 includes a PWM control circuit including switching elements such as IGBTs, converts direct current output from the battery 27 into alternating current based on switching control signals, and supplies the alternating current to the motor 29.

The motor 29 is, for example, a three-phase ac motor, and serves as a drive source for driving the vehicle 10.

The notification unit 30 is configured by a warning lamp, a display of the navigation device, a speaker, and the like, and outputs light, images, sound, and the like to the user based on the control of the charging control unit 24.

Next, details of the power transmission device 300 and the ascending and descending of the power transmission coil 42 will be described with reference to fig. 3A to 3C.

As shown in fig. 3A, a foreign object detection coil 41 is disposed axially above the power transmission coil 42. The foreign object detection coil 41 is a coil for detecting a change in magnetic flux density on the surface of the power transmission device 300 (the surface of the cover 43) to detect a foreign object (e.g., a metal foreign object). In the present embodiment, the axial direction of the power transmission coil 42 is the vertical direction (vertical direction). The magnetic flux density here is a magnetic flux density generated when the power transmission coil 42 is weakly excited.

As shown in fig. 3A, a ferrite core 40 is disposed axially below the power transmission coil 42. A coil fixing portion 46 is disposed below the ferrite core 40. In addition, although not shown, a non-magnetic metal plate may be disposed between the ferrite core 40 and the coil fixing portion 46. The power transmission coil 42 and the foreign object detection coil 41 are fixed to the coil fixing portion 46. Therefore, the coil fixing portion 46 is raised or lowered by the lifting mechanism 17, and the lifting mechanism 17 raises and lowers the power transmission coil 42 and the foreign object detection coil 41 relative to the ground while maintaining the interval (distance) between the power transmission coil 42 and the foreign object detection coil 41. In other words, the power transmission coil 42 and the foreign object detection coil 41 are simultaneously raised or lowered in conjunction with the coil fixing portion 46.

The elevating mechanism 17 is disposed axially below the power transmission coil 42. As shown in fig. 3C, the lifting mechanism 17 includes: two arms 45, an actuator 44, a drive control portion 18, and a bellows 50.

The bellows 50 is made of rubber, resin, metal, or the like. The bellows 50 prevents water, foreign matter, etc. from intruding between the ground fixing portion 15 and the cover 43. The drive control unit 18 receives a signal from the control unit 14, and controls the actuator 44 based on the received signal. The arm 45 is driven by the actuator 44. By driving the arm 45, the power transmission coil 42 and the foreign object detection coil 41 ascend or descend while maintaining the interval between the power transmission coil 42 and the foreign object detection coil 41. In addition, an electric motor, hydraulic pressure, air pressure, or the like is used as the actuator 44.

The cover 43 covers at least the axially upper face of the power transmitting coil 42. In fig. 3A, the cover 43 covers the side surface and the axial upper surface of the power transmitting coil 42. The cover 43 covers the side and upper surfaces of the foreign object detection coil 41. The cover 43 is made of a thermoplastic resin such as polypropylene, for example.

In the standby state shown in fig. 3A, the power transmission coil 42 is lowered by the elevating mechanism 17 to approach the ground. In the standby state, an air layer 60 is formed between the power transmission coil 42 and the cover 43 in the axial direction, more specifically, between the foreign object detection coil 41 and the cover 43 in the axial direction. In the present embodiment, the standby state refers to a state before charging and before foreign object detection.

In the standby state shown in fig. 3A, since the air layer 60 is formed between the power transmitting coil 42 and the cover 43 in the axial direction, even if the temperature of the cover 43 becomes high due to sunshine, it is difficult to transmit the heat of the cover 43 to the power transmitting coil 42. On the other hand, in the case where the air layer 60 is not formed between the power transmission coil 42 and the cover 43 in the axial direction, in other words, in the case where the power transmission coil 42 and the cover 43 are axially close to each other, the heat of the cover 43 is easily transmitted to the power transmission coil 42. Generally, the temperature of the power transmitting coil 42 becomes high during charging. Therefore, when the temperature of the power transmitting coil 42 exceeds the temperature for protecting other components, the charging is stopped. When the power transmission coil 42 and the cover 43 are close to each other in the axial direction, the temperature of the power transmission coil 42 increases from before charging. In this case, since the temperature of the power transmitting coil 42 further increases during charging, the possibility of charging stop becomes high. Therefore, in the present embodiment, in the standby state shown in fig. 3A, that is, in the state before the foreign object is detected, the air layer 60 is formed between the power transmission coil 42 and the cover 43 in the axial direction. More specifically, an air layer 60 is formed between the foreign object detection coil 41 and the cover 43. Even if the temperature of the cover 43 rises due to sunshine, the air layer 60 can restrict the heat transfer of the cover 43 to the power transmitting coil 42. Thereby, the possibility of charging stop is reduced.

In the non-contact power supply, foreign matter detection is performed before charging. When detecting foreign matter, weak excitation weaker than excitation used at the time of charging is used. When a metallic foreign object is present on the upper surface of the cover 43, if the power transmission coil 42 is excited by the excitation used during charging, the cover 43 may be deformed by heat generation of the metallic foreign object. Since the weak excitation is used when detecting the foreign object as described above, when the foreign object detection coil 41 detects the foreign object, the closer the foreign object detection coil 41 is to the foreign object, the higher the detection accuracy of the foreign object. In other words, the closer the foreign object detection coil 41 is to the cover 43, the higher the detection accuracy of the foreign object. In the standby state shown in fig. 3A, the foreign object detection coil 41 is disposed at a predetermined distance from the cover 43 in the axial direction. Therefore, in the foreign object detection state shown in fig. 3B, the elevating mechanism 17 raises the coil fixing portion 46 to minimize the distance between the coil fixing portion 46 and the cover 43. That is, when the foreign object detection coil 41 detects a foreign object, the elevating mechanism 17 elevates the foreign object detection coil 41 so that the distance between the foreign object detection coil 41 and the cover 43 becomes shorter than the predetermined distance shown in fig. 3A. This minimizes the distance between the foreign object detection coil 41 and the cover 43, thereby improving the detection accuracy of the foreign object.

When the elevating mechanism 17 elevates the foreign object detection coil 41, the elevating mechanism 17 elevates the power transmission coil 42 and the foreign object detection coil 41 while maintaining the interval between the power transmission coil 42 and the foreign object detection coil 41 as described above. The reason for maintaining the interval between the power transmission coil 42 and the foreign object detection coil 41 will be described. As described above, the foreign object detection coil 41 detects a change in magnetic flux density on the surface of the cover 43 to detect a foreign object. As a method of detecting the change in the magnetic flux density on the surface of the cover 43, for example, a comparison with a predetermined magnetic flux density is used. As an example, a method is described in which the magnetic flux density generated when the power transmission coil 42 is weakly excited when there is no foreign object is set in advance, and the magnetic flux density at the time of detecting a foreign object is compared with the magnetic flux density set in advance. When the foreign object detection coil 41 detects a change in magnetic flux density, it is determined that a foreign object is present. Here, the predetermined magnetic flux density is detected in a state where the interval between the power transmission coil 42 and the foreign object detection coil 41 is fixed to a predetermined value. That is, if the interval between the power transmitting coil 42 and the foreign object detection coil 41 is changed, the magnetic flux density detected by the foreign object detection coil 41 may be irrelevant to the presence or absence of a foreign object, and the foreign object detection accuracy may be lowered. Therefore, in the present embodiment, when the distance between the foreign object detection coil 41 and the cover 43 is minimized, the elevating mechanism 17 raises the power transmission coil 42 and the foreign object detection coil 41 while maintaining the interval between the power transmission coil 42 and the foreign object detection coil 41. This minimizes the distance between the foreign object detection coil 41 and the cover 43, and maintains the distance between the power transmission coil 42 and the foreign object detection coil 41, thereby improving the accuracy of detecting foreign objects.

In the present embodiment, the foreign object detection state is a state in which the power transmission coil 42 and the power reception coil 22 are paired and the foreign object is detected before charging. However, the foreign object detection state is not limited thereto. The foreign object detection state may be a state in which the foreign object is detected after the positional alignment between the power transmission coil 42 and the power reception coil 22 is completed. In addition, the height of the cover 43 with respect to the ground surface in the standby state shown in fig. 3A is the same as the height of the cover 43 with respect to the ground surface in the foreign object detection state shown in fig. 3B. That is, in the foreign object detection state shown in fig. 3B, the elevating mechanism 17 raises the coil fixing portion 46 but does not raise the cover 43.

In the charging state shown in fig. 3C, the elevating mechanism 17 further raises the coil fixing portion 46 than in the foreign object detection state shown in fig. 3B. Thereby, the cover 43 is lifted while contacting the coil fixing portion 46 via the power transmission coil 42 and the foreign object detection coil 41. That is, the cover 43 rises in conjunction with the rise of the coil fixing portion 46. In the charged state shown in fig. 3C, the lifting mechanism 17 simultaneously lifts the power transmission coil 42 and the cover 43. The distance between the power transmission coil 42 and the power reception coil 22 is shortened by the rise of the power transmission coil 42, and the power transmission efficiency is improved. In the present embodiment, the charged state refers to a state in which the battery is chargeable or a state in which the battery is being charged.

Next, a method of setting the distance between the power transmission coil 42 and the cover 43 in the axial direction will be described with reference to fig. 4 and 5. The methods shown in fig. 4 and 5 are examples, and are not limited to these.

As shown in fig. 4, the longer the distance between the power transmission coil 42 and the cover 43 in the axial direction is, the more difficult the heat of the cover 43 is transmitted to the power transmission coil 42, and the lower the temperature of the power transmission coil 42 is, at a predetermined amount of insolation.

As shown in fig. 4, the longer the distance between the power transmission coil 42 and the cover 43 in the axial direction, the smaller the voltage received by the power receiving coil 22 in the positional alignment of the power transmission coil 42 and the power receiving coil 22. For the alignment, the voltage received by the power receiving coil 22 may be equal to or higher than the voltage V1.

As shown in fig. 5, in the case where the power transmitting coil 42 is affected by sunlight, that is, in the case where the heat of the cover 43 is transferred to the power transmitting coil 42, the temperature of the power transmitting coil 42 may exceed the temperature T for protecting components during charging. Therefore, as shown in fig. 5, when the power transmission coil 42 is not affected by sunlight, the temperature difference Δ T not exceeding the temperature T is set. That is, in the standby state (see fig. 3A), if the temperature of the power transmission coil 42 is equal to or lower than the lower limit value of the temperature difference Δ T, the temperature of the power transmission coil 42 does not exceed the temperature T during the charging period. Thereby, the distance between the power transmission coil 42 and the cover 43 in the axial direction is set to be between the distances L.

Next, an operation example of the contactless power supply system will be described with reference to flowcharts of fig. 6 and 7.

In step S101, the charging control unit 24 determines whether or not the user has performed a charging start operation. The charge start operation is, for example, a user operating a charge start switch provided in the vehicle of the vehicle 10. When the user performs the charge start operation (yes in step S101), the process proceeds to step S103, and the user starts parking. On the other hand, if the user has not performed the charging start operation (no in step S101), the processing stands by.

The process proceeds to step S105, and the charging control unit 24 starts wireless lan communication with the control unit 14 via the wireless communication unit 23. When the vehicle 10 approaches the parking space, the charging control unit 24 transmits a weak excitation request signal to the control unit 14. The communication method is not limited to the wireless lan, and may be other methods.

The process advances to step S107, and the control unit 14 detects the position of the power receiving coil 22. The control unit 14 supplies the electric power for the field weakening to the power transmission coil 42 based on the field weakening request signal received in step S105, and field weakens the power transmission coil 42. The charging control unit 24 detects the power received by the power receiving coil 22, and determines that the power receiving coil 22 is present in the chargeable range when the power received is equal to or greater than a predetermined value.

When the power receiving coil 22 is present within the chargeable range (yes in step S109), the process proceeds to step S111, and the control unit 14 pairs the power transmitting coil 42 and the power receiving coil 22. Pairing refers to authenticating a combination of the power receiving coil 22 and the power transmission coil 42 that supplies power to the power receiving coil 22 in a non-contact manner. If the power receiving coil 22 is not within the chargeable range (no in step S109), the process returns to step S103. When the control unit 14 can pair the power transmission coil 42 and the power reception coil 22 (yes in step S111), the process proceeds to step S114, and the lifting mechanism 17 lifts the coil fixing unit 46. Thereby, the state changes from the standby state to the foreign object detection state. In addition, steps S101 to S113 are in a standby state, and an air layer 60 is formed between the power transmission coil 42 and the cover 43 in the axial direction. If the pairing is not possible (no in step S111), the process proceeds to step S113, and the user stops the vehicle again.

The process advances to step S115, and the control unit 14 activates the foreign object detection coil 41. The foreign object detection coil 41 detects the presence or absence of a foreign object on the upper surface of the cover 43. When there is a foreign object on the upper surface of the cover 43 (yes in step S116), the process proceeds to step S117, and the notification unit 30 notifies the user that there is a foreign object on the upper surface of the cover 43. In step S118, in the case where the user has removed the foreign substance, the process returns to step S116.

If there is no foreign object on the upper surface of the cover 43 (no in step S116), the process proceeds to step S119, and the notification unit 30 notifies the user of the chargeable charge. If the user turns off the ignition (yes in step S121), the process proceeds to step S123. If the user does not turn off the ignition (no in step S121), the processing stands by. The ignition off in the present embodiment includes stopping the vehicle 10 and stopping the power supply system of the vehicle 10. The ignition may be turned off by turning off an ignition switch provided in the vehicle interior of the vehicle 10, or by turning off a power supply system switch provided in the vehicle interior of the vehicle 10.

In step S123, the lifting mechanism 17 further lifts the coil fixing portion 46 to adjust the positions of the power transmission coil 42 and the power reception coil 22 (step S125). Thereby, the state changes from the foreign object detection state to the charging state. In step S127, the foreign object detection coil 41 again detects whether or not a foreign object is present on the upper surface of the cover 43. If there is a foreign object on the upper surface of the cover 43 (yes in step S127), the process proceeds to step S129, and the notification unit 30 notifies the user that there is a foreign object on the upper surface of the cover 43. The process advances to step S131, where the elevating mechanism 17 lowers the coil fixing portion 46. In step S133, in the case where the user has removed the foreign object, the process returns to step S123.

If there is no foreign matter on the upper surface of the cover 43 (no in step S127), the control unit 14 starts charging. The process advances to step S137, and the foreign object detection coil 41 detects whether or not foreign objects are present on the upper surface of the cover 43 during charging. If there is a foreign object on the upper surface of the cover 43 (yes in step S137), the process proceeds to step S145, and the control unit 14 stops charging. If there is no foreign matter on the upper surface of the cover 43 (no in step S137), the process proceeds to step S139, and charging is completed. The process advances to step S141, where the elevating mechanism 17 lowers the coil fixing portion 46. The process advances to step S143, and notification unit 30 notifies the user of the completion of charging.

As described above, according to the contactless power feeding system of the present embodiment, the following operational effects can be obtained.

Before the foreign object detection coil 41 detects the foreign object, the foreign object detection coil 41 is disposed at a predetermined distance from the cover 43 in the axial direction. That is, before the foreign object detection coil 41 detects the foreign object, the air layer 60 is formed between the foreign object detection coil 41 and the cover 43. Thereby, even if the temperature of the cover 43 becomes high due to sunshine, the heat transfer feeding electric coil 42 of the cover 43 can be restricted. Thereby, the possibility of charging stop is reduced.

When the foreign object detection coil 41 detects a foreign object, the elevating mechanism 17 elevates the foreign object detection coil 41 so that the distance between the foreign object detection coil 41 and the cover 43 becomes shorter than a predetermined distance. This shortens the distance between the foreign object detection coil 41 and the cover 43, thereby improving the detection accuracy of the foreign object. At this time, the elevating mechanism 17 raises the power transmission coil 42 and the foreign object detection coil 41 while maintaining the interval between the power transmission coil 42 and the foreign object detection coil 41. This prevents the gap between the power transmission coil 42 and the foreign object detection coil 41 from changing, thereby further improving the accuracy of detecting the foreign object.

(modification 1)

In fig. 3A to 3C, one elevating mechanism 17 raises or lowers the power transmission coil 42, but the elevating mechanism is not limited to one. For example, as shown in fig. 8A, power transmission device 300 may include elevation mechanism 19 in addition to elevation mechanism 17. As shown in fig. 8A, the lifting mechanism 19 includes: two arms 47, an actuator 48 and a bellows 51. The arm 47, the actuator 48, and the bellows 51 are the same as the arm 45, the actuator 44, and the bellows 50 of the lift mechanism 17, and therefore, description thereof is omitted.

In the standby state shown in fig. 8A, the elevating mechanism 17 lowers the coil fixing portion 46 to minimize the distance between the coil fixing portion 46 and the ground fixing portion 15. In the standby state shown in fig. 8A, the lift mechanism 19 raises the cover 43, and an air layer 60 is formed between the power transmission coil 42 and the cover 43 in the axial direction. Thereby, even if the temperature of the cover 43 becomes high due to sunshine, the heat transfer feeding electric coil 42 of the cover 43 can be restricted.

In the foreign object detection state shown in fig. 8B, the elevating mechanism 17 raises the coil fixing portion 46 so that the height of the cover 43 with respect to the ground does not change from the height in the standby state shown in fig. 8A. Thus, the height of the cover 43 is constant, and the distance between the coil fixing portion 46 and the cover 43 is minimized. This also minimizes the distance between the foreign object detection coil 41 and the cover 43, thereby improving the detection accuracy of the foreign object.

In the charging state shown in fig. 8C, the elevating mechanism 17 further raises the coil fixing portion 46 than in the foreign object detection state shown in fig. 8B. This shortens the distance between the power transmission coil 42 and the power reception coil 22, thereby improving the power transmission efficiency.

The foreign matter detection state may be changed to the standby state according to the amount of solar radiation received by the cover 43. The amount of sunshine received by the cover 43 varies depending on the time, weather, and the like. When the cover 43 receives a small amount of sunlight, the temperature of the cover 43 is not high. Therefore, the influence of the heat of the cover 43 on the power transmission coil 42 is also small. Therefore, the air layer 60 may be smaller when the amount of sunlight received by the cover 43 is smaller than when the amount of sunlight is large. When the amount of sunlight received by the cover 43 is close to zero, the air layer 60 may not be provided. Therefore, when the amount of solar radiation received by the cover 43 is small, the foreign object detection state shown in fig. 8B may be changed to the standby state. That is, the foreign object detection state shown in fig. 8B may be a standby state. Thus, the time required for charging can be shortened since there is no time for the standby state to transition to the foreign object detection state.

The amount of sunshine received by the cover 43 can be acquired by the sunshine amount sensor 21 shown in fig. 8A. The elevating mechanism 17 increases the axial distance between the power transmitting coil 42 and the cover 43 as the amount of sunshine increases. At this time, the elevating mechanism 17 may be configured to increase the axial distance between the power transmission coil 42 and the cover 43 in a stepwise manner or in a linear manner according to the amount of solar radiation. That is, when the amount of solar radiation acquired by the solar radiation amount sensor 21 is large, the elevating mechanism 17 lowers the power transmission coil 42 so that the distance in the axial direction between the power transmission coil 42 and the cover 43 becomes longer than when the amount of solar radiation is small. Thereby, even if the temperature of the cover 43 becomes high due to sunshine, the heat of the cover 43 can be prevented from transferring to the electric coil 42. In addition, the method of determining the effect of sunshine is not limited to the sunshine amount sensor 21. The effect of sunlight can also be determined based on the temperature acquired by the temperature sensor. The effect of solar radiation may be determined based on season information, location information provided by power transmission device 300, and the like. In the example shown in fig. 3A to 3C, the solar radiation amount sensor 21 may be provided.

(modification 2)

As shown in fig. 9A, power transmission device 300 may further include an elevation mechanism 33 in addition to elevation mechanism 17. The lifting mechanism 33 includes two arms 49. In the standby state shown in fig. 9A, the elevating mechanism 17 lowers the coil fixing portion 46 to minimize the distance between the coil fixing portion 46 and the ground fixing portion 15. In the standby state shown in fig. 9A, the lift mechanism 33 raises the cover 43, and an air layer 60 is formed between the power transmission coil 42 and the cover 43 in the axial direction. Thereby, even if the temperature of the cover 43 becomes high due to sunshine, the heat transfer feeding electric coil 42 of the cover 43 can be restricted.

In the foreign object detection state shown in fig. 9B, the elevating mechanism 17 raises the coil fixing portion 46 so that the height of the cover 43 with respect to the ground does not change from the height in the standby state shown in fig. 9A. Thus, the height of the cover 43 is constant, and the distance between the coil fixing portion 46 and the cover 43 is minimized. This also minimizes the distance between the foreign object detection coil 41 and the cover 43, thereby improving the detection accuracy of the foreign object.

In the charging state shown in fig. 9C, the elevating mechanism 17 further raises the coil fixing portion 46 than in the foreign object detection state shown in fig. 9B. This shortens the distance between the power transmission coil 42 and the power reception coil 22, thereby improving the power transmission efficiency.

(modification 3)

As shown in fig. 10A, power transmission device 300 may include elevation mechanism 19 and elevation mechanism 33 instead of elevation mechanism 17. In the standby state shown in fig. 10A, the elevating mechanism 19 lowers the coil fixing portion 46 to minimize the distance between the coil fixing portion 46 and the ground fixing portion 15. In the standby state shown in fig. 10A, the lift mechanism 33 raises the cover 43, and an air layer 60 is formed between the power transmission coil 42 and the cover 43 in the axial direction. Thereby, even if the temperature of the cover 43 becomes high due to sunshine, the heat transfer feeding electric coil 42 of the cover 43 can be restricted.

In the foreign object detection state shown in fig. 10B, the elevating mechanism 19 raises the coil fixing portion 46 so that the height of the cover 43 with respect to the ground does not change from the height in the standby state shown in fig. 10A. Thus, the height of the cover 43 is constant, and the distance between the coil fixing portion 46 and the cover 43 is minimized. This also minimizes the distance between the foreign object detection coil 41 and the cover 43, thereby improving the detection accuracy of the foreign object.

In the charging state shown in fig. 10C, the cover 43 is further raised by the lifting mechanism 33 than in the foreign object detection state shown in fig. 10B. The elevating mechanism 19 operates to minimize the distance between the coil fixing portion 46 and the cover 43. This shortens the distance between the power transmission coil 42 and the power reception coil 22, thereby improving the power transmission efficiency.

(modification 4)

In the above embodiment, the case where the height of the cover 43 in the charging state is higher than the height of the cover 43 in the foreign object detection state and the standby state has been described, but the present invention is not limited thereto. The height of the cover 43 in the charging state, the foreign object detection state, and the standby state may be the same. This point will be described with reference to fig. 11A and 11B.

In the standby state shown in fig. 11A, the elevating mechanism 17 lowers the coil fixing portion 46 to form the air layer 60. Thereby, even if the temperature of the cover 43 becomes high due to sunshine, the heat transfer feeding electric coil 42 of the cover 43 can be restricted. In the foreign matter detection state and the charging state shown in fig. 11B, the elevating mechanism 17 raises the coil fixing portion 46 so that the height of the cover 43 with respect to the ground does not change from the height in the standby state shown in fig. 11A. Thus, the height of the cover 43 is constant, and the distance between the coil fixing portion 46 and the cover 43 is minimized. This also minimizes the distance between the foreign object detection coil 41 and the cover 43, thereby improving the detection accuracy of the foreign object. Further, the distance between the power transmission coil 42 and the power reception coil 22 is also shortened, and the power transmission efficiency is improved.

Next, an operation example of the non-contact power supply system according to modification 4 will be described with reference to flowcharts of fig. 12 and 13. Steps S201 to S221 in fig. 12 are the same as steps S101 to S121 in fig. 6. Steps S235 to S245 in fig. 13 are the same as steps S135 to S145 in fig. 7. That is, as shown in fig. 11A and 11B, when the heights of the cover 43 in the charging state, the foreign object detection state, and the standby state are the same, the processing of steps S123 to S133 in fig. 7 is not necessary, and the time required for charging can be shortened.

(modification 5)

As shown in fig. 14A, the power transmission device 300 may use the lifting mechanism 19 instead of the lifting mechanism 17 to lift or lower the coil fixing portion 46. In the standby state shown in fig. 14A, the elevating mechanism 19 lowers the coil fixing portion 46 to minimize the distance between the coil fixing portion 46 and the ground fixing portion 15. Thereby, an air layer 60 is formed between the power transmission coil 42 and the cover 43 in the axial direction. Thereby, even if the temperature of the cover 43 becomes high due to sunshine, the heat transfer feeding electric coil 42 of the cover 43 can be restricted.

In the foreign matter detection state and the charging state shown in fig. 14B, the elevating mechanism 19 raises the coil fixing portion 46 so that the height of the cover 43 with respect to the ground does not change from the height in the standby state shown in fig. 14A. Thus, the height of the cover 43 is constant, and the distance between the coil fixing portion 46 and the cover 43 is minimized. This also minimizes the distance between the foreign object detection coil 41 and the cover 43, thereby improving the detection accuracy of the foreign object. Further, the distance between the power transmission coil 42 and the power reception coil 22 is also shortened, and the power transmission efficiency is improved.

Each function described in the above embodiments may be implemented by one or more processing circuits. The processing circuit includes a programmed processing device such as a processing device including a circuit. The processing circuitry also includes means for orienting a particular Application Specific Integrated Circuit (ASIC), circuit components, etc. into arrangement to perform the functions.

As described above, although the embodiments of the present invention have been described, the present invention should not be construed as being limited by the description and drawings constituting a part of the disclosure. Various alternative embodiments, implementations, and techniques of use will be apparent to those skilled in the art from this disclosure.

For example, in the flowchart shown in fig. 6, when the user performs the charging start operation, a series of controls are started, but the present invention is not limited thereto. As shown in fig. 15, after the ignition is turned off, it may be determined whether or not the user has performed a charge start operation. Sometimes the user stops the vehicle for charging. In addition, although the user does not plan charging, the user may find that charging is performed with a small amount of charging after parking. The process shown in fig. 6 or fig. 15 may contribute to the convenience of the user in various scenarios.

Description of the symbols

14: control unit

15: ground fixing part

17. 19, 33: lifting mechanism

18: drive control unit

20: distance sensor

21: sunshine amount sensor

22: power receiving coil

40: ferrite magnetic core

41: foreign body detection coil

42: power transmission coil

43: cover

44. 48: actuator

45. 47, 49: arm(s)

46: coil fixing part

50. 51: corrugated pipe

60: air layer

100: power supply device

200: power receiving device

300: power transmission device

Claims

1. A power transmission device installed on the ground, comprising:

a power transmission coil that contactlessly transmits power to a power reception coil provided on a vehicle;

a cover that covers at least an axially upper face of the power transmitting coil;

a foreign object detection coil disposed between the power transmission coil and the cover;

a lifting mechanism for maintaining the interval between the power transmission coil and the foreign object detection coil and lifting and lowering the power transmission coil and the foreign object detection coil relative to the ground,

the foreign object detection coil is disposed at a predetermined distance from the cover in the axial direction before detecting a foreign object,

when the foreign object detection coil detects the foreign object, the lifting mechanism lifts the foreign object detection coil so that the distance between the foreign object detection coil and the cover is shorter than the predetermined distance.

2. A method for controlling a power transmitting apparatus installed on the ground,

the power transmission device includes:

the foreign matter detection coil is disposed at a predetermined distance from the cover in the axial direction before detecting the foreign matter,

when the foreign object detection coil detects the foreign object, the foreign object detection coil is raised so that the distance between the foreign object detection coil and the cover is shorter than the predetermined distance.

3. A power transmission device installed on the ground, comprising:

a lifting mechanism for lifting and lowering the power transmission coil relative to the ground;

a sensor that acquires the amount of sunlight received by the cover,

under the circumstances that the amount of sunshine that passes through the sensor acquires is many, with the circumstances that the amount of sunshine is few compare, elevating system makes power transmission coil descends, so that power transmission coil with between the cover the distance in the axial becomes longer.

4. A method for controlling a power transmitting apparatus installed on the ground,

the power transmission device includes:

a lifting mechanism for lifting and lowering the power transmission coil relative to the ground,

when the amount of sunshine received by the cover is large, the power transmission coil is lowered so that the distance in the axial direction between the power transmission coil and the cover is longer than when the amount of sunshine is small.